Referring to FIGS. 1 and 2 there are shown a perspective view of a typical vacuum cleaner and a schematic internal structure of a main body thereof as described in Japanese Laid-Open Publication No. 1987-109531, respectively.
As shown in FIG. 1, the typical vacuum cleaner includes a main body 1 having a dirt collection chamber 6 provided with a connection port 1A; an extension tube 3 provided with a handle 5 at one of its ends for controlling an electric blower 7 as will be described; a suction head 4, installed at the other end of the extension tube 3, for an intake of dirt entraining air; and a hose 2 for interconnecting the connection port 1A to the handle 5, whereby an air-flow path is provided between the main body 1 and the suction head 4.
As shown in FIG. 2, disposed in the main body 1 are an electric blower chamber 8 for mounting therein the electric blower 7 for a generation of suction and the dirt collection chamber 6 provided at the upstream of the suction generated by the electric blower 7. Specifically, in the dirt collection chamber 6 is installed a filter bag 12 made of paper as a dirt collecting means.
During the operation of the vacuum cleaner, dirt-laden air is drawn from a target cleaning surface and travels through the suction head 4, the extension tube 3 and the hose 2, capturing and trapping the dirt in the filter bag 12 and thereby allowing purified air to be discharged through exhaust outlets 9 of an exhaust unit.
Reference numerals 10 and 11 represent a pre-filter and an exhaust air filter, respectively.
In such a vacuum cleaner, it is difficult to filter out fine contaminants such as dandruff, sands, ticks, pollen, mildew and saprophytes and the like despite various attempts to provide an effective filtering thereof, for instance improving dirt drawing efficiency via the suction head 4, improving dirt collection to reduce amount of discharged dirt.
In addition, dirt accumulated in the filter bag 12 generates odor during the operation of the vacuum cleaner. Moreover, when dirt accumulated in the filter bag 12 is not disposed of relatively frequently, saprophytes may breed therein and be discharged via the exhaust outlets 9 during the operation of the vacuum cleaner, which needless to say is very unsanitary.